MICRONEEDLES: NOVEL APPROACH TO TRANDERMAL DRUG DELIVERY SYSTEM

Excellent impervious nature of skin is the greatest challenge that has to be overcome for successfully delivering drug molecules to the systemic circulation by this route. Various formulation approaches used to systemically deliver drug molecules include use of prodrugs/lipophilic analogs, permeation enhancers, sub saturated systems and entrapment into vesicular systems. Further, the adhesive mixture, physical system of the delivery system and release liner influence drug release and its permeation across the skin. The novel microneedle dual-delivery method combines the advantages of hypodermic syringes and transdermal patches. Composed of dozens to hundreds of hollow microneedles, a (1–2) cm2 transdermal patch is applied to the skin to increase its permeability. Arrays of microneedles that are 100–1000 μm in length poke through the top layers of skin and allow micron-scale drugs to pass into the body. The needles are too small to stimulate nerve endings; patients wouldn’t feel any pain when a microneedle injection is performed. This review gives an overview of microneedles for drug delivery applications. The concept of miniaturized needles is presented and defined. Specific requirements for microneedles aimed for transdermal drug delivery are discussed and the scope is delimited. Some of the basic microfabrication methods used to fabricate microneedles is introduced and microneedles for drug delivery presented so far are reviewed and commented.